Electromagnetic device



E. D. MEAD ELECTROMAGNETIC DEVI CE Original Filed Sept. 18, 1922 fi n4 M j W 4/70/04 Patented Dec. 13, 1927.

, UNITED STATES i 1 rnrsur GFFiiit...

EDWARD D. MEAD, 6F CALDW'ELL NEW' EERSEY, ASSIG-TLIOB TO "WESTERN ELECTRIC COMPANY, INCORPORATED, OF NE YORK, N, Y., A CORPORATION OF NEW YORK.

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Original application filed September 18, 192:2, Serial No. $88,837. Divided and this application filed November 27, 1926.

This invention relates to electromagnetic devices, particularly to the core structures therefor, and is a division of application Serial No. 588,837, filed September 18, 1922.

In devices of the character to be hereinafter described it has been found that for simplicity of manufacture and economy of mounting space, the use of a fiat rectangular core port-ion presents the most practical plan whereas for ideal electromagnetic conditions, acylindrical core is required since such a form gives a maximum number of turns for a given length of winding, that is, for a given winding resistance.

The object ofthis invention is to provide an electromagnetic device in which all of the above mentioned manufacturing, mounting and electromagnetic requirements, are.

satisfied.

i In accordance with this invention there is provided a core structure for an electromagnetic device having flat polar projections and integral. therewith an intermediate core portion of greater thickness than said polarportions.

In the preferred form the core structure of this invention is formed by first stamping magnetic sheet metal to form a blank with flat pole portions and an intermediate flat core portion and then swaging the core portion to give it a substantially cylindrical form. In this way the core structure may be formed by simple and economical punching processes.

The invention can be more readily understood by reference to the following detailed description in connection with the drawing in which: Fig. 1 is a perspective view of a relay structure having a core formed in accordance with this invention; Fig. 2 shows the swaged core and associated pole-pieces; Fig. 3 is a sectional view of the magnetic core prior to the swaging process; Fig. i is a sectional view of the core after the swaging process, taken along the line 4e i of Fig. 2; Fig. 5 is a plan view of the apparatus employed in converting the fiat portion into a core of approximate circular cross-section; Fig. 6 is a section along the line 66 of Fig. 5 showing the fiat core in position prior to the swaging process; and Fig. 7 is a section along the line 77 of Fig. 5 showing the core in its form'after the swaging process.

Serial No. 151,038.

Referring to the drawing and particularly to Figs. land 2, a magnet core 20 is provided with two insulating washers 21 and 22 which are provided with slots which admit projections from the pole-pieces 23 and 2d whereby the washers 21 and 22 are held securely on either end of the core portion 20. The washers 21 and 22 cooperate with the core 20 to form a spool for the energizingwindings 25. It will be noted that the thickness of the pole-pieces 23 and 24 is less than that of the core 20 and that the pole-pieces 23 and 24 are flat projections extending from the core 20, the section of which approaches a circle. The pole-piece. 23 is provided with oppositely projecting. portions 26 and 27 which are used for mounting purposes only.

A U-shaped armature 28 is resiliently mounted on extending portions of pole-piece 23 in such a manner as to complete the magnetic circuit between the pole-pieces 23 and 24. V

, Sets of contact springs 29 and 30 are permanently and insulatively mounted on the pole-piece 23 and en tendthe entire length of the relay structure and parallel to the parallel extending portions of the U-shaped armature 28, and are adapted to be operated by the armature 28 through the instrumentality of insulating lugs 31.

A screw 32 is permanently mounted on the extreme end of pole-piece 24 and is provided with a nut 33 which acts as a stop for the backward movement of armature 28 and also provides means for adjusting the air-gap. The terminals extending from contact springs 29 and 30 are adapted to be connected with external circuits which are to be controlled by the operation of the relay. The relay itself operates in a manner similar to any ordinary type of relay.

Referring now to'Figs. 5, 6 and 7, a brief description of the mechanism adapted to produce a substantially round core from a fiat rectangular core follows:

A main supporting plate is provided with a groove extending at right angles to its length which is adapted to slidably accommodate a set of blocks 51 and 52; a sec ond groove extending parallel to the -iength of plate 50 is adapted to receive the polepieces 23 and 24. in such a manner as to bridge the first mentioned groove by the core 20; a second plate member 56 is a duplicate of the supporting plate 50 and is adapted to cooperate with plate 50 to form a mould for the pole-pieces 23 and 24c. The blocks 51 and 52 have their respective ends 54 and 55 rounded as shown in Figs. 6 and 7. The plate 50 may be clamped to the plate 56 in any suitable manner, thereby securely holding the core portion and its associated pole-pieces 23 and 24 in place.

lVhen the pole-pieces 23 and 24 are placed in their respective receptacles in plate 50, and plate 56 is clamped tightly thereon, the blocks 51 and 52 are caused to move simultaneously by any suitable means (not shown) inwardly, and their rounded ends 54 and 55 engage the sides of the flat core portions 20 (Fig. 6). By the continued inward move ment of the members 51 and 52, the core 20 is compressed and assumes a shape which conforms with the area enclosed by the conlining walls of the plates and 56 and the rounded edges 54 and of the blocks 51 and 52 respectively, as is shown in Fig. 7.

The rounded core not only gives an in crease in ampere-turns driving force, a decrease in copper cost, since a smaller size wire can be used to obtain the same number of turns and resistance as with a flat core, and increases the height of winding space available, but also improves the 'i'nanufacturing process because the winding operation is much easier with arounded core than with a flat one. In winding a flat core the wire is intermittently slack and tense which tends to stretch the wire and the sharp corners at times damage the wire.

hat is claimed is:

1. I11 an electromagnetic device, a magnetic core piece having flat pole portions and integral therewith an intermediate core portion of rounded cross-section and materially thicker than said flat portions.

2. A magnetic core piece having flat pole portions and integral therewith an intermediate core portion of rounded cross section and materially thicker than said flat pole portions, one of said pole portions hav ing laterally extending mounting lugs integral therewith.

3. A magnetic core piece having llat pole portions and integral therewith an intermediate core portion of a substantially oval cross section the lesser axis of which is materially greater than the thickness of said flat portions, and the greater axis of which is materially less than the width of any part of said fiat portions.

4. A magnetic core piece having a rear flat pole portion provided with laterally extending integral mounting lugs and adapted to have an armature mounted thereon, a front flat pole portion adapted to cooperate with an armature and integral with said pole portions an intermediate core portion of rounded cross section materially thicker than said flat pole portions, and of substantially the same cross sectional area as said "front pole portion.

In witness whereof, I hereunto subscribe my name this 26th day of November A. D., 1926.

EDVARD D. MEAD. 

